Deep oil gas resources are important alternative fields of future oil gas resource development. Water injection and gas injection are important measures for the development of deep oil reservoirs, but long-term water injection or gas injection aggravates the heterogeneity of the reservoir, and cross flow is easy to occur, so that the water content of an oil well rises quickly, and the development level is reduced to some extent. The profile control and water shutoff of the ultra-deep oil reservoir is an important technology for improving the development effect of water injection or gas injection, and the plugging agents such as polymer particle gel, inorganic particles, foam and the like developed at present are widely applied to the aspect of profile control and water shutoff. However, ultra-deep oil reservoir faces complex and severe reservoir conditions of ultra-high temperature (more than or equal to 150° C.), ultra-high salinity (more than or equal to 200,000 mg/L) and ultra-high pressure (more than or equal to 50 MPa), a conventional particle gel system is poor in stability and easy to degrade, inorganic particles are difficult to transport deeply, a foam construction process is complex, validity period is short, and the application of a conventional plugging agent system in a deep oil reservoir is limited.
CN103232839B discloses a water shutoff agent suitable for water shutoff and profile control of high-temperature and high-salinity oil reservoirs. The water shutoff agent consists of a main agent, a cross-linking agent, a stabilizing agent and water, wherein the main agent is sulfonated tannin extract or sodium humate; the cross-linking agent is a combination of aldehyde cross-linking agent and phenolic cross-linking agent, and the stabilizing agent is water glass and non-ionic polyacrylamide. It can be suitable for water shutoff and profile control of oil layers with the temperature of 90° C. to 150° C. and the degree of mineralization of more than 2.0 multiplied by 105 mg/L. But the condition of the oil reservoir with the temperature of more than or equal to 150° C. is not involved, and the application of profile control and water shutoff in an ultra-deep oil reservoirs is limited.
CN104927825B discloses a temperature-resistant salinity-resistant dispersed particle gel nitrogen foam composite profile control and flooding system. The system comprises a gas phase and a liquid phase, wherein the gas phase is nitrogen, the liquid phase is a combination of a foaming agent, a foam stabilizer and water, the system can resist the temperature of 130° C., resist the degree of total mineralization of 17 multiplied by 104 mg/L, resist calcium ion of 1.0 multiplied by 104 mg/L and resist magnesium ion of 1.0 multiplied by 104 mg/L. However, the conditions of the oil reservoir with the temperature of more than or equal to 150° C. and the degree of mineralization of more than or equal to 2.0 multiplied by 105 mg/L are not involved, the foam field construction is relatively complex, and it is difficult to meet the requirement of profile control and water shutoff of the ultra-deep oil reservoir.
Therefore, in order to improve the profile control and water shutoff effect of the ultra-deep oil reservoir to the maximum extent, a new plugging agent system needs to be developed, and a multidimensional intercalation low-temperature expandable graphite system capable of meeting the requirements of ‘ advancing, moving far and plugging’ needs to be developed. The initial expansion temperature of the existing expandable graphite is generally higher, generally more than or equal to 300° C., and the complete expansion temperature is between 900° C. and 1000° C. The expansion can not be realized under the condition of the ultra-deep oil reservoir, and the deep profile control and water shutoff of the ultra-deep oil reservoir are difficult to realize.